Bacterial Strains Having an Outstanding Ability to Produce Menaquinone

ABSTRACT

The invention relates to bacterial strains having an outstanding ability to produce menaquinone and to applications thereof.

FIELD OF THE INVENTION

The invention relates to bacterial strains having an outstanding abilityto produce menaquinone.

BACKGROUND OF THE INVENTION

Menaquinone or vitamin K2 is involved in the carboxylation of certainglutamate residues in proteins to form gamma-carboxyglutamate residues(abbreviated Gla-residues). The modified residues are often (but notalways) situated within specific protein domains called Gla domains.Gla-residues are usually involved in binding calcium. The Gla-residuesare essential for the biological activity of all known Gla-proteins(Furie B, Bouchard B A, Furie B C; Blood 93 (6): 1798-808). To date, 14human proteins with Gla domains have been discovered, and they play keyroles in the regulation of three physiological processes, such as bloodcoagulation (prothrombin (factor II), factors VII, IX, X, protein C,protein S and protein Z); bone metabolism (osteocalcin, also called boneGla-protein (BGP), and matrix gla protein (MGP); and vascular biology.

Accordingly, menaquinone deficiency may induce several pathologies suchas for example bleeding, coagulation dysfunctions, osteoporosis . . . .Typically, the groups of patients which are considered to beparticularly exposed to a menaquinone deficiency are the new born, theelderly, the patients having liver, bile or intestinal dysfunctions, andpatients having chronic antibiotic treatment.

Several methods have been proposed in the prior art to supplement themenaquinone deficiency of these patients. One of these methods consiststo administer to these patients menaquinone-producing bacteria. Indeed,menaquinone is produced by the bacteria of the intestinal flora, and inparticular by the bacteria of the species Escherichia coli, Bacillussubtilis and Bacteroides subsp. Menaquinone is also produced by severallactic acid bacteria, such as for example the bacteria of the generaBifidobacterium, Lactococcus, Leuconostoc, Enteroccocus andPropionibacterium. In particular, a specific variant of Lactococcuslactis subsp. cremoris having the ability to produce more menaquinonethan the corresponding wild type strain has been recently disclosed inWO 2008/040793.

However, having strains capable of producing higher amounts ofmenaquinone would be very interesting.

SUMMARY OF THE INVENTION

The invention relates to bacterial strains having an outstanding abilityto produce menaquinone. Indeed, during their research, the inventorshave found that the particular strains according to the inventionpresent an exceptional ability to produce menaquinone compared to theother strains known to date. These strains have been deposited under theBudapest Treaty under the following accession numbers: CNCM I-4128, DSM23476, DSM 23477, DSM 23478, DSM 23479.

The invention particularly relates to the use of these strains andvariants thereof for producing menaquinone.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to bacterial strains having an outstanding abilityto produce menaquinone as compared to other strains known to date.

An object of the invention concerns a strain of Lactococcus lactissubsp. cremoris deposited by Danisco France SAS (20, rue de Brunel,75017 Paris, France) under the Budapest Treaty on 24th of February 2009at the Collection Nationale de Cultures de Microorganismes (CNCM,Institut Pasteur, 25, rue du Docteur Roux, 75724 Paris cedex 15, France)under number CNCM I-4128, or a variant thereof. The strain CNCM I-4128or variants thereof produce high quantities of menaquinone. Inparticular, the inventors have shown that the strain CNCM I-4128 produceat least 7 μg of menaquinone per 100 g of milk fermented with saidstrains when measured in a Test A.

Typically, the variants of the strain CNCM I-4128 produce at least 7 μg,particularly at least 8 μg, still particularly at least 9 μg, moreparticularly at least 10 μg, still more particularly at least 11 μg andmost particularly at least 12 μg of menaquinone per 100 g of milkfermented with said variant when measured in a Test A according to theinvention.

Test A is fully described in the experimental section. Briefly, Test Acomprises the following steps:

-   -   inoculating two flasks comprising 100 mL of skimmed UHT milk,        with 5.10⁴ to 10⁷ cfu/mL of the strain to be tested,    -   incubating the inoculated flasks without stirring at a constant        temperature selected in the range from 23° C. to 30° C. in a        water bath,    -   measuring and recording the evolution of the pH in one of the        two flasks with a pH probe of a Cinac System (Ysebaert system),    -   stopping the incubation when the pH reaches 4.60+/−0.1 by        cooling down to 6° C. the flask wherein the pH has not been        measured,    -   storing said flask at 6° C. during 14 h to 20 h,    -   homogenizing the milk manually,    -   performing a chemical extraction of menaquinone and measuring        the quantity of menaquinone following the protocol P.

In another embodiment of the invention, the variants of the strain CNCMI-4128 produce at least 200 μg, particularly at least 230 μg, moreparticularly at least 260 μg of menaquinone per 100 g of freeze-driedcells when measured in a Test B. Test B is fully described in theexperimental section. Briefly, Test B comprises the following steps:

-   -   culturing 1.10² to 1.10⁷ cfu/ml of the strain to be tested        during 14 h to 20 h in 50 ml of M17-lactose broth medium (Biokar        BK088HA) at 30° C.,    -   centrifuging 25 mL of the culture at 8000 rpm during 10 minutes,    -   discarding the supernatant and resuspending the pellet with 25        mL of a tryptone salt solution (0.1% tryptone, 0.85% salt),    -   centrifuging the resuspended culture at 8000 rpm during 10        minutes,    -   discarding the supernatant and resuspending the pellet in 25 ml        of reconstituted milk powder at 10% (w/w),    -   placing the cell suspension in a freeze dryer,    -   obtaining between 2 and 4 grams of freeze-dried cells,    -   performing the chemical extraction of menaquinone and measuring        the quantity of menaquinone following the protocol P.

Protocol P is the following:

A sample consisting of 10 ml of fermented milk (for test A) or 10 mL ofa ten times dilution in ethanol/water (50/50 V/V) of freeze-dried cells(for test B) is mixed with 5 ml of HCl 1N. The sample is then heated at100° C. during 10 min in a water bath. Then, 10 ml of isopranol areadded in the tube. The tube is placed 10 min in a water bath at 22° C.(+/−3° C.) equipped with ultra sounds. 5 ml of hexane are added in thetube. The tube is mixed by vortexing during 5 min.

The suspension is centrifuged at 4600 rpm during 5 min. Then the organicphase is harvested and again centrifuged during 5 min at 4600 rpm. Theorganic phase is then harvested and concentrated with a speed vac systemin order to obtain a dry product. The dry product is rehydrated with 1ml ethanol and filtrate on 0.45 μm filter. This extract is injected in aHPLC system. Separation and detection of menaquinone are performed usingmethods described in Hojo K. et al., “Quantitative measurement oftetrahydromenaquinone-9 cheese fermented by propionibacteria”, J. dairyScience, 2007, 90, 9. 4078-4083. The detection is performed by afluorometer after post-column reduction of menaquinone by Zn. Vitamin K1is used as internal standard for extraction/purification steps and MK-4(Sigma V9378) is used as external calibration for quantification.

The invention also concerns a strain of Lactococcus lactis spp. cremorisdeposited by Danisco Deutschland GmbH (Busch-Johannsen-Str. 1, 25899Niebüll, Germany) under the Budapest Treaty on 24th of March 2010 at theDeutsche Sammlung von Mikroorganismen and Zellkulturen (DSMZ,Inhoffenstr. 7B, D-38124 Braunschweig, Germany) under number DSM 23476,or a variant thereof.

The strain DSM 23476 or variants thereof produce high quantities ofmenaquinone. The variants of the strain DSM 23476 typically produce atleast 25 μg of menaquinone per g of freeze-dried cells when measured ina Test C according to the invention.

In one embodiment, the variants of the strain DSM 23476 typicallyproduce at least 30 μg, particularly at least 35 μg, still particularlyat least 40 μg, more particularly at least 45 μg, still moreparticularly at least 50 μg, again more particularly at least 55 μg, andmost particularly at least 60 μg of menaquinone per g of freeze-driedcells when measured in a Test C according to the invention.

The invention also concerns a strain of Lactococcus lactis spp lactisdeposited by Danisco Deutschland GmbH (Busch-Johannsen-Str. 1, 25899Niebüll, Germany) under the Budapest Treaty on 24th of March 2010 at theDeutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ,Inhoffenstr. 7B, D-38124 Braunschweig, Germany) under number DSM 23477,or a variant thereof.

The strain DSM 23477 or variants thereof produce high quantities ofmenaquinone.

The variants of the strain DSM 23477 typically produce at least 15 μg ofmenaquinone per g of freeze-dried cells when measured in a Test Caccording to the invention.

In one embodiment, the variants of the strain DSM 23477 typicallyproduce at least 20 μg, particularly at least 25 μg, still particularlyat least 30 μg, more particularly at least 35 μg, still moreparticularly at least 40 μg of menaquinone per g of freeze-dried cellswhen measured in a Test C according to the invention.

The invention also concerns a strain of Lactococcus lactis spp cremorisdeposited by Danisco Deutschland GmbH (Busch-Johannsen-Str. 1, 25899Niebüll, Germany) under the Budapest Treaty on 24th of March 2010 at theDeutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ,Inhoffenstr. 7B, D-38124 Braunschweig, Germany) under number DSM 23478,or a variant thereof.

The strain DSM 23478 or variants thereof produce high quantities ofmenaquinone.

The variants of the strain DSM 23478 typically produce at least 30 μg ofmenaquinone per g of freeze-dried cells when measured in a Test Caccording to the invention.

In one embodiment, the variants of the strain DSM 23478 typicallyproduce at least 35 μg, particularly at least 40 μg, still particularlyat least 45 μg, more particularly at least 50 μg, still moreparticularly at least 55 μg of menaquinone per g of freeze-dried cellswhen measured in a Test C according to the invention.

Briefly, Test C according to the invention comprises the followingsteps: 1) Culturing the strain: 1.A) the strain stored in a viablephysiological state at temperature below −20° C. is first sub-culturedin a synthetic medium (Lactose 50 g/l, Yeast Extract powder 36 g/l, MnSO₄H₂0 1 g/l, Mg SO₄7 H₂0 1 g/l) at 30° C.+/−2° C. overnight,

1.B) from 2% to 5% (V/V) of the first culture obtained after step 1.A)is then sub-cultured in synthetic medium from 10 h to 24 h, at atemperature comprised between 25° C. and 35° C., a pH maintained in therange 5.0-7.5 by alkali addition, and dissolved oxygen kept below 2%during the entire step,

2) Concentrating the strain: the cultured strain obtained after step1.B) is concentrated with a centrifuge separator until a concentrationcomprised between 2.10¹⁰ cfu/ml and 6.10¹¹ cfu/ml is obtained; theconcentrate thus obtained is then cooled at a temperature below 12° C.;

3) Preserving the strain: 30 to 70% (w/w) of skimmed milk powder isdirectly added to the concentrate, frozen at −55° C., pelletized toobtain frozen pellets, and freeze dried in a freeze drier to achieve aAw with in the range 0.05-0.35 (measured with 3TE Aqualab Ltd device),

4) Extracting and measuring the quantity of menaquinone following theprotocol Q according to the invention.

Protocol Q comprises the following steps:

-   -   1) Extracting menaquinone (all the steps of the extraction are        carried out in subdued light to prevent the deterioration of K        vitamins):        -   Put 10 mL of a solution containing 0.5 g of freeze dried            material in 100 mL of nanopure water in a 50 mL amber Falcon            tube (Ø30×115 mm—Ref 525-0397 VWR),        -   Add 1004 of internal standard (Vitamin K1 at 20 μg/mL in            ethyl alcohol) and 5 mL of hydrochloric acid 1N,        -   Put the tube in a 100° C. bath during 10 min,        -   After cooling, add 10 mL of isopropanol,        -   Sonicate the sample during 10 min,        -   Add 5 mL of hexane, shake the sample for 5 min, Centrifuge 5            min at 3760 g and collect the organic layer (upper layer) in            a 15 mL amber Falcon tube (Ø17×120 mm—Ref 525-0395 VWR),            Repeat this step twice,    -   After collecting the two organic layers, they are evaporated to        dryness in a vacuum evaporator Speed-Vac (about 30 min),        -   Dissolve the residue in 1 mL of ethanol,        -   The sample is filtered through a Nylon 0.45 μm filter and            placed in a HPLC vial,    -   2) measuring the quantity of menaquinone in the sample by HPLC.

HPLC Analysis:

High performance liquid chromatography coupled to a fluorimetry detectoris used in order to analyse vitamin K. Different forms of vitamin K areseparated on a reverse phase column and reduced through a post column.

Identified and measured forms of vitamin K2:

K₂ vitamin (MK-n) MK-4 MK-5 MK-6 MK-7 MK-8 MK-9 MK-10

K₁ vitamin used as internal standard

Products and Solutions:

-   -   K1 Vitamin, Sigma V3501-1G, CAS 84-80-0    -   K2 Vitamin, (MK-4), Sigma V9378-250MG, CAS 11032-49-8

Mobile Phase:

-   -   In a flask with 830 mL of methanol and 170 mL of ethanol, add        0.68 g of sodium acetate, 1.36 g of zinc chloride and 300 μL of        acetic acid.    -   Shake the mix and sonicate it during 10 min.

The analysis is carried out by an Agilent HPLC 1100 in reverse phasewith a fluorescence detector. In order to improve vitamin K'ssensibility detection, it's reduced after separation in hydroquinone bychemical reduction with zinc metal. Hydroquinones are more fluorescentthan quinones.

Reduction: Quinone + 2 e⁻ + 2 H⁺ →H₂Q E ° = +0.70 V (Hydroquinone)Oxidation: Zn →Zn²⁺ + 2e⁻ E ° = −0.76 V Balance: Quinone + 2 H⁺ + Zn→H₂Q(Hydroquinone) + Zn²⁺

Analytical Conditions:

-   -   Column: Capcell Pak 5 μm SG-C18, 250×4.6 mm (Phenomenex)    -   Post column reduction: Reactor post column zinc, 20×4 mm.    -   Mobile phase: 83% of methanol        -   17% of ethanol        -   5 mM of sodium acetate        -   10 mM of ZnCl₂        -   5 mM of acetic acid    -   Flow: 1 mL/min (isocratic elution)    -   Column temperature: 55° C.    -   Detector: λ_(ex)=220 nm, λ_(em)=436 nm    -   Injection volume: 10 μL

Menaquinone Quantification:

The internal standard, Vit K1, is used to calculated the yield ofextraction/purification for each sample preparation. For calibration ofthe technique, a calibration curve has been obtained for K2 Vitamin,(MK-4), Sigma V9378-250MG. The response coefficient of MK-4 is appliedfor the other form of MK. It allows to transform peak surface area intoMk-4 equivalent concentration in the sample for each MK-form.Furthermore, for each form of MK's, the concentration in mass for eachform is calculated taking into account the differences in molecular massbetween menaquinone MK-4 and MK form considered. For example, themolecular mass of MK4 is 512 g/mol, the molecular mass of MK9 is 852g/mol, therefore 1 μg of MK4 will give exactly the same peak surfacearea than 1.66 μg of MK9. This principle of calculation is used for eachMK form.

The invention also concerns a strain of Propionibacterium freudenreichiisubsp. Shermanii deposited by Danisco Deutschland GmbH(Busch-Johannsen-Str. 1, 25899 Niebüll, Germany) under the BudapestTreaty on 24th of March 2010 at the Deutsche Sammlung vonMikroorganismen and Zellkulturen (DSMZ, Inhoffenstr. 7B, D-38124Braunschweig, Germany) under number DSM 23479, or a variant thereof.

The strain DSM 23479 or variants thereof produce high quantities ofmenaquinone. A variant of the strain DSM 23479 typically produces atleast 15 μg of menaquinone per 100 g of milk fermented with said variantwhen measured in a Test D according to the invention.

In one embodiment, a variant of the strain DSM 23479 typically producesat least 15 μg, particularly at least 20 μg, still particularly at least25 μg of menaquinone per 100 g of milk fermented with said variant whenmeasured in a Test D according to the invention.

Test D according to the invention comprises the following steps:

-   -   inoculating two flasks comprising 100 mL of a skimmed UHT milk        supplemented with 1.6 ml of pure D-L lactate and 0.2% of yeast        extract powder and heat treated 20 minutes at 110° C., with        5.10⁴ to 10⁷ cfu/mL of the strain to be tested,    -   incubating the inoculated flasks without stirring at a constant        temperature selected in the range from 23° C. to 30° C. in a        water bath,    -   measuring and recording the evolution of the pH in one of the        two flasks with a pH probe of a Cinac System (Ysebaert system),    -   stopping the incubation when the pH reaches 4.60+/−0.1 by        cooling down to 6° C. the flask wherein the pH has not been        measured,    -   storing said flask at 6° C. during 14 h to 20 h,    -   homogenizing the milk manually,    -   performing a chemical extraction of menaquinone and measuring        the quantity of menaquinone following the protocol P according        to the invention.

According to the invention, by “variant” it is meant:

-   -   a natural variant of the strain according to the invention, i.e.        a variant obtained spontaneously from the strain according to        the invention after incubation in a selection medium. A natural        variant is thus obtained without any genetic manipulation of the        operator but only by natural mutation of the strain and        selection of the strain in an appropriate medium, or    -   a variant of the strain according to the invention comprising at        least one mutation in their genome, said mutation being induced        by genetic engineering, for instance by directed mutagenesis or        random mutagenesis. For instance, random mutagenesis can be        performed with UV radiations or mutagenic compounds such as        nitrous acid, ethyl-methanesulfonate,        N-Methyl-N′-nitro-N-nitrosoguanidine, N-ethyl-N-nitrosourea,        acridine orange, proflavine.

By “mutation” according to the invention, it is meant the addition,deletion, or the substitution of at least one nucleotide in the genomeof the strain according to the invention.

The strains according to the invention or variants thereof, are thusvery interesting in term of health benefits, but also in term ofmarketing. For example, in Europe when a product contains at least 11.5μg of menaquinone per serving size, more particularly per 100 g or per100 mL of product, it can be labelled as “source of” vitamin K2.

Another object of the invention concerns the use of the strains orvariants thereof according to the invention for producing menaquinone.An application of the invention is the use of the outstanding propertiesof the strains and variants thereof according to the invention toproduce important amounts of menaquinone at an industrial scale. Themenaquinone can then be extracted from the cultures of strains accordingto the invention and be used in all kinds of preparations, for instancein pharmaceutical preparations, feed and food preparations such as adairy product, or dietary supplements.

The invention thus also concerns a method for producing menaquinone,comprising the step of culturing a strain or a variant thereof accordingthe invention in a substrate. Said substrate can be selected from anyappropriate substrate known by the skilled person. Examples ofappropriate substrates are milk substrates, in particular selected fromthe group consisting of natural or reconstituted milk, skimmed orotherwise, milk-based media and media based on products of dairy origin.

Another object of the invention is a strain or a variant thereofaccording to the invention, for use in a method for treatment of thehuman or animal body.

Typically, the strains or variants thereof according to the inventionare useful in the treatment of the diseases associated with a deficiencyin menaquinone, as for instance bone, vascular and/or skin healthdiseases such as osteoporosis, cardiovascular diseases, blood pressuredysfunctions, blood clotting, loss of skin elasticity.

The invention thus relates to a method for treating a disease selectedfrom the group comprising bone diseases such as osteoporosis; vasculardiseases such as cardiovascular diseases, blood pressure dysfunctionsand blood clotting; and skin diseases, such as loss of skin elasticity;said method comprising the step of administering to a patient in needthereof, a therapeutically effective amount of a strain or of a variantthereof according to the invention.

The invention also relates to a method for improving calcium fixation onthe bones, maintaining or improving the bone structure and/orresistance, and/or improving the bone development, said methodcomprising the step of administering to a patient in need thereof, aneffective amount of a strain or of a variant thereof according to theinvention. Alternatively, the invention relates to the strains orvariants thereof according to the invention, for use in a method forimproving calcium fixation on the bones, maintaining or improving thebone structure and/or resistance, and/or improving the bone development.

The term “treating” or “treatment”, as used herein, means reversing,alleviating, inhibiting the progress of, or preventing the disorder orcondition to which such term applies.

As used herein, “patient” refers to a human or animal that may benefitfrom the administration of a strain or a variant thereof as recitedherein.

By a “therapeutically effective amount” of a strain or a variant thereofas described previously, it is meant a sufficient amount to treat thedisease, at a reasonable benefit/risk ratio applicable to any medicaltreatment.

In a particular embodiment of the method for treatment of the invention,the strain or a variant thereof can be used alive or under a specificpreserved state. When the strain or variant thereof is used in apreserved state, the strain has been preferably previously cultured toenrich its content in menaquinone. By “preserved state” it is meant astrain that has been dried, freeze-dried or frozen for example. Thestrain or a variant thereof may also be used after having beeninactivated, for instance by heat treatment, by chemical treatmentand/or by other treatments known by the skilled person in the art.

Another aspect of the invention concerns the preparation of productsenriched in menaquinone by using the strains or variants thereofaccording to the invention. These products are thus particularly usefulfor supplementing any deficiency in menaquinone occurring in a patientin need thereof. Such deficiency in menaquinone is for instanceencountered in the newborn infants, individuals who suffer from liverdamage or disease (i.e. alcoholics), people with cystic fibrosis,inflammatory bowel diseases or those who have recently had abdominalsurgeries. Groups which may suffer from secondary vitamin K deficiencyinclude bulimics, those on stringent diets and those takinganticoagulants.

Accordingly, the invention concerns the use of a strain or a variantthereof according to the invention for preparing a product. This productis typically selected from the group consisting of a dietary supplement,a pharmaceutical preparation, a food preparation and a feed preparation.In a particular embodiment, in these products, the strain or a variantthereof can be used alive or under a specific preserved state. When thestrain or variant thereof is used in a preserved state, the strain hasbeen preferably previously cultured to enrich its content inmenaquinone. By “preserved state” it is meant a strain that has beendried, freeze-dried or frozen for example. The strain or a variantthereof may also be used after having been inactivated, for instance byheat treatment, by chemical treatment and/or by other treatments knownby the skilled person in the art.

The invention also relates to a product typically selected from thegroup comprising of a dietary supplement, a pharmaceutical preparation,a food preparation and a feed preparation, wherein said productcomprises a strain or a variant thereof according to the invention.

According to the invention, by “dietary supplement” it is meant aproduct or a composition that is intended to supplement the diet of thehuman or of an animal. A dietary supplement according to the inventionis typically intended for ingestion in pill, capsule, tablet, or liquidform.

According to the invention, by “pharmaceutical preparation” it is meanta preparation that is intended to be used in a method for treatment ofthe human or animal body. In the context of the invention, the term“treatment”, as used herein, means reversing, alleviating, inhibitingthe progress of, or preventing a disorder or condition. Typically, thepharmaceutical preparation according to the invention comprises thestrain or a variant thereof according to the invention together with apharmaceutically acceptable carrier.

According to the invention, by “food preparation” it is meant apreparation that is intended to feed a human.

According to the invention, by “feed preparation” it is meant apreparation that is intended to feed an animal.

In a particular embodiment of the invention, said product is a foodpreparation. More particularly, the food preparation is a dairy product.Within the meaning of the invention, by “dairy product” it is meantfermented milk, a yogurt, a matured cream, a cheese, a fromage frais, amilk drink, a dairy product retentate, a processed cheese, a creamdessert, a cottage cheese or an infant milk. Still typically, the dairyproduct according to the invention comprises milk of animal and/or plantorigin.

Another aspect of the invention concerns the application of the strainsand variants thereof according to the invention to enrich the content ofa product in menaquinone. Accordingly, the invention relates to a methodfor enriching the menaquinone content of a product selected from thegroup consisting of a dietary supplement, a pharmaceutical preparation,a food preparation and a feed preparation, comprising the step of addingto said product a strain or a variant thereof according to theinvention. In a particular embodiment of this method, the strain or avariant thereof can be used alive or under a specific preserved state.When the strain or variant thereof according to the invention is used ina preserved state, the strain has been preferably previously cultured toenrich its content in menaquinone. By “preserved state” it is meant astrain that has been dried, freeze-dried or frozen for example. Thestrain or a variant thereof may also be used after having beeninactivated, for instance by heat treatment, by chemical treatmentand/or by other treatments known by the skilled person in the art.

The present invention is better illustrated below using the exampleswhich follow. These examples are given only by way of illustration ofthe subject-matter of the invention, of which they in no way constitutea limitation.

EXAMPLES Example 1 Measurement of the Production of Menaquinone by theStrain CNCM I-4128, Following TEST B

The strain CNCM I-4128 has been compared to 23 other strains belongingto the Lactococcus lactis species for their production of menaquinone(following TEST B).

For each strain, the following protocol has been followed:

-   -   culturing 1.10² to 1.10⁷ cfu/ml of the strain during 18 h in 50        ml of M17-lactose broth medium (Biokar BK088HA) at 30° C.,    -   centrifuging 25 mL of the culture at 8000 rpm during 10 minutes,    -   discarding the supernatant and resuspending the pellet with 25        mL of a tryptone salt solution (0.1% tryptone, 0.85% salt),    -   centrifuging the resuspended culture at 8000 rpm during 10        minutes,    -   discarding the supernatant and resuspending the pellet in 25 ml        of reconstituted milk powder at 10% (w/w),    -   placing the cell suspension in a freeze dryer,    -   obtaining between 2 and 4 grams of freeze-dried cells.

The chemical extraction of menaquinone and the measurement of itsquantity have been performed according to the following protocol:

The freeze-dried cells obtained in Test B are diluted ten times inethanol/water (50/50 V/V). 10 mL of this dilution are mixed with 5 ml ofHCl 1N. The sample is heated at 100° C. during 10 min in a water bath.Then, 10 ml of isopranol are added in the tube. The tube is placed 10min in a water bath at 22° C. (+/−3° C.) equipped with ultra sound. 5 mlof hexane are added in the tube. The tube is mixed by vortexing during 5min.

The suspension is centrifuged at 4600 rpm during 5 min. Then the organicphase is harvested and again centrifuged during 5 min at 4600 rpm. Theorganic phase is then harvested and concentrated with a speed vac systemin order to obtain a dry product. The dry product is rehydrated with 1ml ethanol and filtrate on 0.45 μm filter. This extract is injected in aHPLC system. Separation and detection of menaquinone are performed usingmethods described in Hojo K. et al., “Quantitative measurement oftetrahydromenaquinone-9 cheese fermented by propionibacteria”, J. dairyScience, 2007, 90, 9. 4078-4083. The detection is performed by afluorometer after post-column reduction of menaquinone by Zn. Vitamin K1is used as internal standard for extraction/purification steps and MK-4(Sigma V9378) is used as external calibration for quantification.

The results are presented in Table 1, which shows the difference ofproduction of menaquinone between the CNCM I-4128 and 23 other strainsbelonging to the Lactococcus lactis species (which were Lactococcuslactis subsp. cremoris or Lactococcus lactis subsp. lactis strains).Data are expressed in μgrams per 100 grams of freeze dried cells.

TABLE 1 Comparison of production of menaquinone (Vit. K2) for 24 strainsof Lactococcus lactis Total vitamin K2 expressed in Strains μg/100 g offreeze dried cells 1 78 2 49 CNCM I-4128 267 3 91 4 48 5 60 6 59 7 79 862 9 94 10 42 11 68 12 38 13 12 14 57 15 73 16 68 17 79 18 28 19 36 20130 21 73 22 63 23 94

The results of this experiment clearly show that the strain CNCM I-4128has an outstanding ability to produce menaquinone compared to the 23other strains tested.

Example 2 Measurement of the Production of Menaquinone by the StrainCNCM I-4128, Following TEST A

The measure of the production of menaquinone by the strain CNCM I-4128in the milk (following TEST A) has been repeated 11 times, according tothe following protocol:

-   -   inoculating two flasks comprising 100 mL of skimmed UHT milk,        with 5.10⁴ to 10⁷ cfu/mL of the strain CNCM I-4128,    -   incubating the inoculated flasks without stirring at a constant        temperature selected in the range from 23° C. to 30° C. in a        water bath,    -   measuring and recording the evolution of the pH in one of the        two flasks with a pH probe of a Cinac System (Ysebaert system),    -   stopping the incubation when the pH reaches 4.60+/−0.1 by        cooling down to 6° C. the flask wherein the pH has not been        measured,    -   storing said flask at 6° C. during 14 h to 20 h,    -   homogenizing the milk manually.

The chemical extraction of menaquinone and the measurement of itsquantity have then been performed according to the following protocol:10 ml of milk obtained previously have been mixed with 5 ml of HCl 1N.The same protocol as in Example 1 has then been followed to perform theextraction of menaquinone and to measure its content.

Results are presented in table 2 hereinafter:

TABLE 2 Production of vitamin K2 by CNCM I-4128 during milk maturationfor temperature range between 23° C. and 30° C., results for 11independent experiments Total vitamin K2 expressed in Experiment n°μg/100 g of fermented milk 1 7.3 2 9.9 3 12 4 12.3 5 15.2 6 9.8 7 12.2 812 9 16.3 10 8.7 11 11.6

These results show that the average production of CNCM I-4128 is 11.6μg/100 g of fermented milk with a standard deviation of 2.5 μg/100 g.

Example 3 Measurement of the Production of Menaquinone by Strains CNCMI-4128, DSM 23476, DSM 23477 and DSM 23478 by test C

CNCM I-4128:

Freeze dried material has been produced according to test C and themenaquinone content in the freeze dried product has been evaluatedthanks to protocol Q for extraction/purification and dosage.

TABLE A vitamin K2 concentration for CNCM-I-4128 - test C and protocol Qcoef- fi- Average cient MK- MK- MK- Total K2 of 6 7 MK-8 MK-9 10 K2 μg/gof vari- Sample ng/g ng/g ng/g ng/g ng/g μg/g LYO ation CNCM 1865 744348307 155025 4812 374 378.1 3.6% I-4128 1736 6593 43810 156743 4061 3672139 6912 57037 158733 4171 393

DSM 23476 and DSM 23477:

Freeze dried material has been produced according to test C and themenaquinone content in the freeze dried product has been evaluatedthanks to protocol Q for extraction/purification and dosage.

TABLE B vitamin K2 concentration for DSM 23476 and DSM 23477 - test Cand protocol Q - two trials test C+ protocol Q per strain Average MK-MK- Total K2 coefficient 6 7 MK-8 MK-9 K2 μg/g de of Sample ng/g ng/gng/g ng/g μg/g LYO variation DSM 4026 5451 16842 24928 51.25 45.2 13.2%23476 3623 4965 14361 16372 39.32 Trial n^(o)1 3698 5008 15866 2041644.99 DSM 5104 7199 22166 30561 65.03 62.3 8.3% 23476 4860 6565 1914425782 56.35 Trial n^(o)2 5649 8027 23437 28541 65.66 DSM 1960 3980 1314510208 29.30 28.4 4.0% 23477 1795 3903 11518 9898 27.12 Trial n^(o)1 16903855 12719 10529 28.80 DSM 1422 3309 15970 18408 39.11 42.1 11.1% 234771308 3176 16598 18554 39.64 Trial n^(o)2 1290 3093 19051 23975 47.41

DSM 23478:

Freeze dried material has been produced according to test C and themenaquinone content in the freeze dried product has been evaluatedthanks to protocol Q for extraction/purification and dosage.

TABLE C vitamin K2 concentration for DSM 23478 - for differentextractions/purification step with the same freeze dried materialobtained with Test C. MK- MK-4 MK-5 MK-6 MK-7 MK-8 MK-9 10 Total K2coefficient of Test ng/g ng/g ng/g ng/g ng/g ng/g ng/g μg/g variation 1135.8 <100 178.7 1827.2 17597.1 60772.4 792.4 81.3 79.3 2.9% 2 124.1<100 205.6 1935.2 18461.4 59126.8 695.7 80.5 3 204.2 <100 <100 1806.315680.9 57854.0 555.1 76.1 4 176.0 <100 450.4 1941.5 16657.6 59727.2618.8 79.6

Example 4 Measurement of the Production of Menaquinone by DSM 23479 byTest D

Strain DSM 23479 has been cultured as described in test D. Menaquinoneproduction has then be measured according to protocol P. Results arepresented in the table D hereinafter:

TABLE D Production of Vitamin K2 by DSM 23479 - test D MK- MK- MK- MK-MK- K2 totale 4 5 6 7 8 MK- μg/ Test ng/ ng/ ng/ ng/ ng/ MK-9 10 100 mL# mL mL mL mL mL ng/mL ng/mL (μg/100 g) 1 <1 <1 <1 <1 <1 3.8 261.4 26.5

1. Use of a strain selected from the group consisting of the straindeposited under the Budapest Treaty on 24th of February 2009 at the CNCMunder number CNCM I-4128, or a variant thereof, the strain depositedunder the Budapest Treaty on 24th of March 2010 at the DSMZ under numberDSM 23476, or a variant thereof, the strain deposited under the BudapestTreaty on 24th of March 2010 at the DSMZ under number DSM 23477, or avariant thereof, the strain deposited under the Budapest Treaty on 24thof March 2010 at the DSMZ under number DSM 23478, or a variant thereof,and the strain deposited under the Budapest Treaty on 24th of March 2010at the DSMZ under number DSM 23479, or a variant thereof, for producingmenaquinone.
 2. A strain selected from the group consisting of thestrain deposited under the Budapest Treaty on 24th of February 2009 atthe CNCM under number CNCM I-4128, or a variant thereof, the straindeposited under the Budapest Treaty on 24th of March 2010 at the DSMZunder number DSM 23476, or a variant thereof, the strain deposited underthe Budapest Treaty on 24th of March 2010 at the DSMZ under number DSM23477, or a variant thereof, the strain deposited under the BudapestTreaty on 24th of March 2010 at the DSMZ under number DSM 23478, or avariant thereof, and the strain deposited under the Budapest Treaty on24th of March 2010 at the DSMZ under number DSM 23479, or a variantthereof, for use in a method for treatment of the human or animal body.3. The strain or variant thereof according to claim 2, wherein saidmethod for treatment is a method for treatment of a disease selectedfrom the group comprising bone diseases such as osteoporosis; vasculardiseases such as cardiovascular diseases, blood pressure dysfunctionsand blood clotting; and skin diseases, such as loss of skin elasticity.4. Use of a strain selected from the group consisting of the strain ofdeposited under the Budapest Treaty on 24th of February 2009 at the CNCMunder number CNCM I-4128, or a variant thereof, the strain depositedunder the Budapest Treaty on 24th of March 2010 at the DSMZ under numberDSM 23476, or a variant thereof, the strain deposited under the BudapestTreaty on 24th of March 2010 at the DSMZ under number DSM 23477, or avariant thereof, the strain deposited under the Budapest Treaty on 24thof March 2010 at the DSMZ under number DSM 23478, or a variant thereof,and the strain deposited under the Budapest Treaty on 24th of March 2010at the DSMZ under number DSM 23479, or a variant thereof, for preparinga product selected from the group consisting of a dietary supplement, apharmaceutical preparation, a food preparation and a feed preparation.5. A product comprising a strain selected from the group consisting ofthe strain deposited under the Budapest Treaty on 24th of February 2009at the CNCM under number CNCM I-4128, or a variant thereof, the straindeposited under the Budapest Treaty on 24th of March 2010 at the DSMZunder number DSM 23476, or a variant thereof, the strain deposited underthe Budapest Treaty on 24th of March 2010 at the DSMZ under number DSM23477, or a variant thereof, the strain deposited under the BudapestTreaty on 24th of March 2010 at the DSMZ under number DSM 23478, or avariant thereof, and the strain deposited under the Budapest Treaty on24th of March 2010 at the DSMZ under number DSM 23479, or a variantthereof.
 6. The product according to claim 5, wherein said product isselected from the group consisting of a dietary supplement, apharmaceutical preparation, a food preparation and a feed preparation.7. The product according to claim 5, wherein said product is a dairyproduct selected from the group comprising a fermented milk, a yogurt, amatured cream, a cheese, a fromage frais, a milk drink, a dairy productretentate, a processed cheese, a cream dessert, a cottage cheese or aninfant milk.
 8. The product according to claim 7, wherein said dairyproduct comprises milk of animal and/or plant origin.
 9. A method forenriching the menaquinone content of a product comprising the step ofadding to said product a strain selected from the group consisting ofthe strain deposited under the Budapest Treaty on 24th of February 2009at the CNCM under number CNCM I-4128, or a variant thereof, the straindeposited under the Budapest Treaty on 24th of March 2010 at the DSMZunder number DSM 23476, or a variant thereof, the strain deposited underthe Budapest Treaty on 24th of March 2010 at the DSMZ under number DSM23477 or a variant thereof, the strain deposited under the BudapestTreaty on 24th of March 2010 at the DSMZ under number DSM 23478 or avariant thereof, and the strain deposited under the Budapest Treaty on24th of March 2010 at the DSMZ under number DSM 23479 or a variantthereof.
 10. The method according to claim 9, wherein said product isselected from the group consisting of a dietary supplement, apharmaceutical preparation, a food preparation and a feed preparation.11. A strain selected from the group consisting of the strain depositedunder the Budapest Treaty on 24th of February 2009 at the CNCM undernumber CNCM I-4128, or a variant thereof, the strain deposited under theBudapest Treaty on 24th of March 2010 at the DSMZ under number DSM23476, or a variant thereof, the strain deposited under the BudapestTreaty on 24th of March 2010 at the DSMZ under number DSM 23477, or avariant thereof, the strain deposited under the Budapest Treaty on 24thof March 2010 at the DSMZ under number DSM 23478, or a variant thereof,and the strain deposited under the Budapest Treaty on 24th of March 2010at the DSMZ under number DSM 23479, or a variant thereof, for use in amethod for improving calcium fixation on the bones, maintaining orimproving the bone structure and/or resistance, and/or improving thebone development.
 12. A strain of Lactococcus lactis subsp. cremorisdeposited under the Budapest Treaty on 24th of February 2009 at the CNCMunder number CNCM I-4128, or a variant thereof.
 13. The strain or thevariant thereof according to claim 12, wherein said variant produces atleast 7 μg, particularly at least 9 μg, more particularly at least 11 μgof menaquinone per 100 g of milk fermented with said strain or variantthereof when measured in a Test A.
 14. The strain or the variant thereofaccording to claim 12, wherein said variant produces at least 200 μg,particularly at least 230 μg, more particularly at least 260 μg ofmenaquinone per 100 g of freeze-dried cells when measured in a Test B.15. The product according to claim 6, wherein said product is a dairyproduct selected from the group comprising a fermented milk, a yogurt, amatured cream, a cheese, a fromage frais, a milk drink, a dairy productretentate, a processed cheese, a cream dessert, a cottage cheese or aninfant milk.
 16. The product according to claim 15, wherein said dairyproduct comprises milk of animal and/or plant origin.
 17. The strain orthe variant thereof according to claim 13 wherein said variant producesat least 200 μg, particularly at least 230 μg, more particularly atleast 260 μg of menaquinone per 100 g of freeze-dried cells whenmeasured in a Test B.